Ironbridge Power Station in Shropshire is to close this afternoon after 46 years in operation.
Energy firm E.ON said the station had reached the number of operating hours set by EU environmental regulations and was closing as a result.
The station, originally coal-fired, was converted to burn wood pellets in 2013 to lower emissions ahead of its planned closure this year.
More than 400 workers were employed at the site at its peak of generation, but that has been reduced to around 130.
Some workers will start the decommissioning process, which will take until 2017.